Device for separating sheet-type products

ABSTRACT

A friction wheel singler for singling bank notes includes a singler roller  1  with grooves  2 , and retaining wheels  14  cooperating with the grooves  2 . The retaining wheels  14  have friction areas  14   a  and sliding areas  14   b  such that both a sliding area  14   b  and a friction area  14   a  cooperate with each groove  2  of the singler roller  1 . Such a friction singler is particularly suitable for longitudinal singling of narrow bank notes and prevents skewing of the sheet to be singled during the singling process.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a National Phase of International Application SerialNo. PCT/EP03/05644, filed May 28, 2003.

FIELD OF THE INVENTION

This invention relates to a friction singler for singling sheet-shapedvalue documents, such as bank notes, checks or the like. The frictionsingler comprises a sheet magazine for receiving a stack of sheets, apicking device with a singler element having, for contacting andconveying the sheets to be singled from the sheet magazine, one or morefriction elements with grooves extending in the transport direction ofthe sheets to be singled, and a retaining device which forms with thesingler element a singler gap through which the sheets to be singled areconveyed out of the sheet magazine, and which has friction areas of highcoefficient of friction and sliding areas of low coefficient of frictioncooperating with the grooves of the singler element.

DESCRIPTION OF THE BACKGROUND ART

There are different technical concepts for singling stacks of sheetssuch as bank-note bundles so that the singled bank notes can be suppliedto a testing sensor system which determines the authenticity,qualitative nature, denomination or other characteristic properties ofthe bank notes.

The present application deals with the concept of friction singlers. Ina friction wheel singler, the friction elements of a singler roller forexample act on the surface of a bank note of a bank-note stack, the thuscontacted bank note being conveyed in a transport direction due tofriction by rotation of the singler roller while the other bank notes ofthe bank-note stack are held back by a retaining device. The retainingdevice and the singler roller to this end form a singler gap throughwhich the bank note is conveyed. The singler roller has groovesextending in the transport direction of the bank notes to be singled andcapable of being slightly engaged by the retaining device. Theengagement depth is adjustable.

To make sure the bank note contacted by the singler roller is conveyedand the other bank notes of the bank-note stack are held back, thesingler roller must exert on the bank note in the singler gap a singlingforce or feed force that is greater than the retaining force exerted onthe bank note by the retaining device on the opposite side of thesingler gap. The retaining device can be realized for example as aretaining roller or retaining pad or runner, which can be mounted eitherrigidly or so as to rotate against the transport direction.

To adjust the ratio of feed force to retaining force to a desired fixedvalue, the singler roller can be provided with friction elements whosefriction linings have a considerably higher coefficient of friction thanthe corresponding friction linings of the retaining device, the ratio offriction being for example about 2:1.

It has proved disadvantageous in this procedure that the differentfriction materials of the singler roller and the retaining device partlyhave very different operating behavior, for example with respect toresistance to environmental influences, moisture absorption, temperaturecoefficient, aging and wear resistance. This can lead to differentservice lives and influences the ratio of friction, which can lead tosingling errors including a multiple pick, by which more than one sheetis grasped and conveyed by the singler roller.

For avoiding these problems, a friction wheel singler was developedwherein the same friction material, or friction material with the samecoefficient of friction, is used for singler roller and retaining device(DE 100 08 135 A1). To make sure the singler roller force acting on thesheet material to be singled is sufficiently greater than the forceexerted by the retaining device despite the use of substantially thesame friction material for retention and singling, it is provided thatthe contact area between the sheet material and the friction elements ofthe singler roller is substantially greater than the contact areabetween the sheet material and the friction areas of the retainingdevice. This is obtained by the retaining roller engaging adjacentcircumferential grooves of the singler roller alternately with amaterial of high coefficient of friction (“friction area”) and with amaterial of low coefficient of friction (“sliding area”). If thecoefficient of friction of the sliding areas of the retaining device isnegligibly low, a ratio of coefficients of friction of about 2:1 againresults because the friction materials of the retaining device and thesingler roller are otherwise the same.

The friction wheel singler according to DE 100 08 135 A1 is particularlysuitable for transverse singling of bank notes, by which bank notes aresingled with their longitudinal edge leading. When the friction wheelsingler is used as a longitudinal singler, by which bank notes aresingled with their narrower transverse edge leading, bank notes areoccasionally skewed during singling, however, which can lead to jammingin the singler gap or to a jam in the subsequent transport path.

SUMMARY OF THE INVENTION

The problem of the present invention is to propose a friction singler ofthe type stated at the outset for singling sheet material, in particularfor bank notes, which reduces the problem of skewing of the sheetmaterial during singling, in particular when the friction singler isused as a longitudinal singler.

This problem is solved by a friction singler with the features disclosedherein. Advantageous embodiments and developments of the invention arealso disclosed herein.

It is therefore provided that a groove of the singler element cooperatesboth with a friction area and with a sliding area of the retainingdevice. In the prior art, each groove cooperates either with a frictionarea or with a sliding area of the retaining device. It is suspectedthat the known design leads during singling of a bank note to a torqueacting on the bank note when the bank note is transported for exampleonly over two grooves of the singler element. Then only a friction areaof the retaining device acts on the bank note with the first groove anda sliding area thereof with the second groove in different places. Ifthe feed force responsible for transporting the bank note does not acton the middle of the bank note, it causes a torsional moment whichcannot be compensated by the only effective friction area. Thistorsional moment is held responsible for the abovementioned skew andjamming of sheet material in the singler gap.

Since it is now provided that at least one, preferably at least two, ofthe grooves of the singler element cooperate both with a friction areaand with a sliding area of the retaining device, a frictional guide ofthe sheet material over two grooves is achieved while the frictionalcontact surface or the feed force is the same, thereby reducing thedanger of skewing of the sheet material.

The order of friction and sliding areas cooperating with the individualgrooves can be different for different grooves, viewed transversely tothe transport direction, and is preferably opposite for adjacentgrooves. In the last-named case the torques acting on the transportedsheet material in each groove substantially cancel each other outthrough the torque produced in the adjacent groove and acting in theopposite direction, thereby additionally improving the guide propertiesof the friction singler.

The retaining device is preferably formed by one or more retainingwheels which have the friction and sliding areas. This is advantageousin particular when the singler element is also formed as a rotatingsingler roller, thereby keeping the rubbing wear on the individualcomponents low.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will hereinafter be described by way of example withreference to the attached drawings, in which:

FIG. 1 shows schematically a cross section of a friction wheel singleralong the singling direction of the bank notes,

FIG. 2 shows the friction wheel singler from FIG. 1 schematically in aplan view according to the prior art,

FIG. 3 shows the friction wheel singler from FIG. 1 schematically in aplan view according to the invention,

FIG. 4 a shows a detail of a front view of the friction wheel singler asin FIGS. 1 and 2 according to the prior art, and

FIG. 4 b shows a detail of a front view of the friction wheel singler asin FIGS. 1 and 3 according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The friction wheel singler according to FIG. 1 is constructedsubstantially as described in DE 100 08 135 A1. Therefore a detaileddescription of these per se known components will be omitted here.

In particular, the singler roller 1 and the retaining roller 14, asknown in the art, have circumferential grooves 2 which are mutuallyoffset and adapted in their width such that the retaining rollers 14,which are formed to be adjustable in height, can engage the grooves ofthe singler roller 1 to increase the frictional forces.

This is shown in a plan view in FIG. 2 by the example of a frictionwheel singler according to the prior art. Two retaining rollers 14 eachhave a frictional friction area 14 a and a smooth sliding area 14 b ofapproximately equal size. With the friction areas 14 a and sliding areas14 b the retaining rollers 14 engage the circumferential grooves 2 ofthe singler roller 1. When the lowermost bank note 5 a of the bank-notestack 5 is singled there are thus in each case two linear contacts ofthe bank note 5 a between the retaining rollers 14 and the singlerroller 1 in each circumferential groove 2. Depending on whether acontact with a friction area or a contact with a sliding area isinvolved, the terms “friction edge” or “sliding edge” are also used.

Because of its division into friction areas 14 a and sliding areas 14 b,the retaining roller 14 exerts only half as much frictional force on thebank note 5 a to be singled as the friction segment 3 of the singlerroller 1, which consists of the same friction material as the frictionareas 14 a of the retaining roller 14. A suitable friction material isin particular cast polyurethane. In contrast, the singler roller 1 isotherwise made of a synthetic material of low coefficient of frictionjust like the sliding areas 14 b of the retaining wheel 14.

Singling of the bank-note stack 5 placed in the input pocket 16 of thefriction wheel singler takes place as follows: the lowermost bank note 5a next to be singled lies with its leading edge against the singlerroller 1. The force with which the bank-note stack 5 deposited in thesheet magazine 16, formed here as an oblique guiding plate, acts on thesingler roller 1 is determined alone by gravity and therefore depends onthe weight and thus substantially on the height of the bank-note stack5.

With the help of the feed rollers 18 likewise equipped with frictionsegments, the bank notes are pushed to the singler gap 19 preferably ata speed corresponding to the transport speed of the bank note aftersingling has taken place. The singler gap 19 is formed by the opposingsurface areas of the singler roller 1 and the retaining roller 14.

When the singler roller 1 has rotated under the control of the adjustingdevice 15 so far that the area of the friction segment 3 is rotated intoan effective position, that is, into the area of the singler gap 19, thefeed force considerably outweighs the retaining force, so that a sheet 5a to be singled is conveyed through the singler gap 19. When thefriction segment 3 moves out of the area of the singler gap 19 in thecourse of further rotation of the singler roller 1, the next waitingbank note is held back until the friction segment 3 of the singlerroller takes effect on the singler gap 19 again.

FIG. 2 shows the friction wheel singler with two retaining rollers 14formed according to the prior art. Upon transverse singling, by whichbank notes lie with their broader longitudinal edges against the singlergap 19, both retaining rollers 14 act on the sheet 5 a to be singled. Atorque exerted on the bank note by one retaining roller is compensatedby the other retaining roller. Upon singling in the longitudinal format,by which bank notes lie with their narrower transverse edge against thesingling gap 19, however, it can happen that bank notes lie only againstone of the two retaining rollers 14. Since the thereby acting feed forcewill not act on the middle of the bank note to be singled, said roller14 exerts on the bank note in addition to the feed force a torqueperpendicular to the feed direction, which in this case is notcompensated by a second retaining roller. Thus, the bank note can bejammed in the singler gap 19 or therebehind.

FIG. 3 shows a schematic view of the friction wheel singler as in FIG. 2but with retaining rollers 14 modified according to the invention.Accordingly, the retaining rollers 14 still have both friction areas 14a and sliding areas 14 b, but the retaining rollers 14 engage eachgroove 2 of the singler roller 1 both with a friction area 14 a and witha sliding area 14 b, so that they form both a friction edge and asliding edge with each groove 2.

This is presented in detail again in FIG. 4 b in comparison with theprior art according to FIG. 4 a, whereby FIGS. 4 a and 4 b each showonly a singler roller 1 with two circumferential grooves 2 and aretaining roller 14 with friction areas 14 a and sliding areas 14 bcooperating with the circumferential grooves 2 of the singler roller 1.

While the retaining roller 14 according to the prior art as in FIG. 4 ahas a single friction area cooperating with one of the twocircumferential grooves 2 of the singler roller 1 and a single slidingarea 14 b cooperating with the other of the two circumferential grooves2 of the singler roller 1, the friction areas 14 a and sliding areas 14b in the retaining roller 14 according to the invention as in FIG. 4 bare divided up so that both a friction area 14 a and a sliding area 14 bof the retaining roller 14 cooperate with each circumferential groove 2of the singler roller 1. In contrast to the prior art, in which theretaining roller 14 forms either two sliding edges or two friction edgeswith each of the circumferential grooves 2 of the singler roller 1, theinventive retaining roller 14 thus forms a sliding edge and a frictionedge with each circumferential groove 2 of the singler roller 1. Thus,any torque acting perpendicular to the transport direction of the banknotes BN is compensated: when the order of sliding edge/friction edge isreversed with circumferential grooves 2 adjacent to each other, theproduced torque is exactly balanced with respect to the central plane Alocated between the circumferential grooves.

LIST OF REFERENCE SIGNS

-   1 Singler element, singler roller-   2 Groove, circumferential groove-   3 Friction element-   5 Stack of sheets-   5 a Sheet to be singled-   14 Retaining device, retaining roller-   14 a Friction area-   14 b Sliding area-   15 Adjusting device-   16 Sheet magazine-   18 Feed roller-   19 Singler gap-   A Central plane-   BN Bank note

1. A friction singler for singling sheet-shaped value documents (5),comprising: a sheet magazine (16) for receiving a stack of sheets (5), apicking device with a singler element (1), the singler element having,for contacting and conveying the sheets (5 a) to be singled from thesheet magazine (16), one or more friction elements (3) with at least onegroove (2) extending in the transport direction of the sheets (5 a) tobe singled, and a retaining device (14) which forms with the singlerelement (1) a singler gap (19) through which sheets (5 a) to be singledare conveyed from the sheet magazine (16), and which has friction areas(14 a) of high coefficient of friction and sliding areas (14 b) of lowcoefficient of friction cooperating with the at least one groove (2) ofthe singler element (1), characterized in that the at least one groove(2) of the singler element (1) cooperates both with a friction area (14a) and with a sliding area (14 b) of the retaining device (14).
 2. Afriction singler according to claim 1, characterized in that the singlerelement (1) has at least two grooves (2), extending in the transportdirection of the sheets (5 a) to be singled, and that each cooperatesboth with a friction area (14 a) and with a sliding area (14 b) of theretaining device (14).
 3. A friction singler according to claim 2,characterized in that the order of friction and sliding areas (14 a, 14b) cooperating with the grooves (2), viewed transversely to thetransport direction, is different for different grooves (2).
 4. Afriction singler according to claim 3, characterized in that the orderis opposite for adjacent grooves (2).
 5. A friction singler according toclaim 1, characterized in that the retaining device (14) comprises oneor more retaining wheels having the friction areas (14 a) and slidingareas (14 b).
 6. A friction singler according to claim 1, characterizedin that the singler element (1) is a singler roller.
 7. The frictionsingler of claim 1, wherein said documents are bank notes.
 8. Thefriction singler of claim 2, wherein said at least two grooves includeall grooves.
 9. A friction singler according to claim 2, characterizedin that the retaining device (14) comprises one or more retaining wheelshaving the friction areas (14 a) and sliding areas (14 b).
 10. Afriction singler according to claim 3, characterized in that theretaining device (14) comprises one or more retaining wheels having thefriction areas (14 a) and sliding areas (14 b).
 11. A friction singleraccording to claim 4, characterized in that the retaining device (14)comprises one or more retaining wheels having the friction areas (14 a)and sliding areas (14 b).
 12. A friction singler according to claim 7,characterized in that the retaining device (14) comprises one or moreretaining wheels having the friction areas (14 a) and sliding areas (14b).
 13. A friction singler according to claim 8, characterized in thatthe retaining device (14) comprises one or more retaining wheels havingthe friction areas (14 a) and sliding areas (14 b).
 14. A frictionsingler according to claim 2, characterized in that the singler element(1) is a singler roller.
 15. A friction singler according to claim 3,characterized in that the singler element (1) is a singler roller.
 16. Afriction singler according to claim 4, characterized in that the singlerelement (1) is a singler roller.
 17. A friction singler according toclaim 5, characterized in that the singler element (1) is a singlerroller.
 18. A friction singler according to claim 7, characterized inthat the singler element (1) is a singler roller.
 19. A friction singleraccording to claim 8, characterized in that the singler element (1) is asingler roller.